Drilling Jet larger

jus wondering if anyone knows what drill bit i should use to get me to a 85 jet size?
Thank you

85 on a stock carb?? i dont think so..

You won't find a drill bit that will get you exactly an 85 jet, not anything easily obtainable at least. A #66 (wire gauge) bit will be an 84 jet (83.8 to be exact) and a #65 bit will be a 89 jet (88.9). Man your heavily modded engine must be thirsty. You sure you need it that big?

EDIT- Oh ok, now I get it, gonna use it with the adjustable jet needle......?

you can find drill bits in the proper sizes, if you have access to a good fractional drill bit set, if not just buy the jet,

The smallest bit available in a fractional size drill bit set is 1/16". 1/16" would be a size 159 jet. Aside from specialty drill bits that are probably hard to find or costly, for drill bits smaller than 1/16" you will need to get "wire gauge" drill bits which are numbered from 1-80.

set i use at work goes smaller then a 1/16th,(have to look) but you are right they are very expensive and are hard to work with, not the size bits to use free hand, still easier to buy jets

A hobby mini drill set is great for enlarging jets. For a stock Cag, a #73 (0.024) drill will help to stop bogging at top end.


Here is a sample set of bits and a good price. Local hobby shops often carry these also.

http://www.widgetsupply.com/page/WS/...drill-bit/WB05

Hey Fritz

Which drill bit do you use for specific jet sizes? I just purchased that drill bit set from the website you listed. Thanks.

Eric

this is an excerpt from zero4's post at PBX:
wire gauge = inch = mm = jet size
73 = .0240 = .6096 = 61
72 = .0250 = .6350 = 63.5
71 = .0260 = .6604 = 66
70 = .0280 = .7112 = 71
69 = .0295 = .7493 = 75
68 = .0310 = .7874 = 79

and a link to bit size to mm conversions I found:
http://www.dave-cushman.net/elect/wiregauge.html

Well, there's another person who I assume has a 60 jet(?) stock. I've measured so many stock jets that I don't remember (trying to find those 68 jets that are supposedly out there) how many and all the ones I've came across were just smaller than 63. A #73 bit would pass right through them.

Eric as tblummer posted the list again, those are the sizes you are limited too. I can convert the rest of them if you would like since I know you need jets that are higher up there. Or just go to the link tha tblummer gave.

When you get your "wire gauge" bits that you ordered, next to each number bit it should tell you the size of the bit in inches. Just convert inches to metric and your set.

Thanks!

Hey Zero (will), the link that Fritz wrote down...are those the wire gauge drill bits you were talking about?

Thanks Will. I got this message right after I replied back.

With the stock cag carb, the biggest a person should go, really, is about a 68-70. Anything bigger than that, you'll bog a lot. The reason I use 80-85 size jets, is because of the dellorto. The dellorto, as you know, doesnt use a needle for more adjustability on fuel, as do the stock carbs. With the stock carb, as long as you have the main set to a 68 or 70, you can play around with the needle to fine tune the fuel mixture.

Thanks again bro.

Ok, lets try this. Jets are measured in 100ths of a millimeter. So, for example, a # 68 jet has a 68/100 millimeter diameter hole. Or, a 0.0268 (rounded up from 0.02677) hole in inches. So then you would probably use a #70 drill, which is 0.028, or a #71 drill which is 0.0260 Got it???

DRILL SIZE 60 (.0400")

DRILL SIZE 61 (.0390")

DRILL SIZE 62 (.0380")

DRILL SIZE 63 (.0370")

DRILL SIZE 64 (.0360")

DRILL SIZE 65 (.0350")

DRILL SIZE 66 (.0330")

DRILL SIZE 67 (.0320")

DRILL SIZE 68 (.0310")

DRILL SIZE 69 (.0292")

DRILL SIZE 70 (.0280")

DRILL SIZE 71 (.0260")

DRILL SIZE 72 (.0250")

DRILL SIZE 73 (.0240")

DRILL SIZE 74 (.0225")

DRILL SIZE 75 (.0210")

DRILL SIZE 76 (.0200")

DRILL SIZE 77 (.0180")

DRILL SIZE 78 (.0160")

DRILL SIZE 79 (.0145")

DRILL SIZE 80 (.0135")

No problem. Yes those are "wire gauge" bits. You are good to go.

Here's the whole list so you can copy and paste the list for reference:

wire gauge = inch = mm = jet size
#73 = .0240 = .6096 = 61
#72 = .0250 = .6350 = 64
#71 = .0260 = .6604 = 66
#70 = .0280 = .7112 = 71
#69 = .0295 = .7493 = 75
#68 = .0310 = .7874 = 79
#67 = .0320 = .8128 = 81
#66 = .0330 = .8382 = 84
#65 = .0350 = .8890 = 89
#64 = .0360 = .9144 = 91
#63 = .0370 = .9398 = 94
#62 = .0380 = .9652 = 97
#61 = .0390 = .9906 = 99
#60 = .0400 = 1.016 = 102

(I'll post a "How-To" tonight on "rejetting the stock carb")
EDIT- Ok, I guess maybe I won't. I was also gonna post on how to rethread to accomodate dell orto jets but I see there already is a post with that info in it, although some of the info is not accurate at all.

Hey Will

Go ahead and do that dellorto writeup. The writeup I posted was from mm64, and he may not have had all the correct info. It'd be a great addition to the cag how-to's. If you wanna do a writeup for someone who just wants to drill out their jet, go ahead and do so, and send it in. It'll definitely get posted. Info like this is extremely valuable.

Eric

Ok I will do that. If I don't get around to it tonight, I'll definitely get it done by tomorrow.

No worries bro.

Hey I'm going to SD this weekend to ride. I might be up in the valley on Saturday though. If you're in town, or if I'm in town, hook up!

-E

****, the one weekend I can't ride, your in town, lol. SD, Amago? I hope you'll be able to make it out with us to Amago on the 30th (next month) to race. Me and Freddy (MinimotoPilot) will definitely be there. I have to work on Sat. but regardless my cag is being torn apart and I just sent my DM fairings to the shop to get a makeover. We'll definitely have to hook up one of these days.

dont think its a good idea to drill the jet, buy a new one!